


Internalized pressure

by Creativekai03



Category: Undertale (Video Game)
Genre: Alternate Universe - Porn, Anal Plug, Anal Sex, Creampie, Dom/sub, Ecto-Genitalia (Undertale), Ecto-Penis (Undertale), Ecto-Tentacles (Undertale), Female Frisk (Undertale), Inflation, Magic, No More Resets (Undertale), Oral Sex, Other, Porn, Rough Sex, Sans (Undertale) Remembers Resets, Sex Magic, Sex Toys, Spells & Enchantments, Tentacles, Undertale Monsters on the Surface, Uterus, Vaginal Sex, Vibrators
Language: English
Status: Completed
Published: 2020-07-01
Updated: 2020-07-01
Packaged: 2021-03-05 03:33:21
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,084
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25017811
Author URL: https://archiveofourown.org/users/Creativekai03/pseuds/Creativekai03
Summary: You and sans wanted to try something new in the bedroom, with an enchantment that allows you to not breathe and sans's magic this will be a night not to forget.
Relationships: Frisk/Sans (Undertale)
Kudos: 22





	Internalized pressure

It was a normal day in the underground, you had decided to not go to the surface based upon last reset - where the humans killed them all. You had become quite close to the short skeleton and often would be seen holding hands. Papyrus was always out trying to make new friends or testing you with puzzles.  
After your first time being intimate with sans you learned that his magic was amazing, he could make it do almost anything and today you planned to test that with him. After discussing it with sans yesterday he had went out and gotten an enchantment for you, from gerson. You had asked sans before about "breathing" as a skeleton and he said they don't, this sparked curiosity about what it'd be like if you didn't need to breathe - sans hadn't told you what he had planned for today, only that it'd be new and exciting.  
As soon as papyrus left to go to undyne's house for training you both walked upstairs into sans's room. Ever since you had gotten together sans kept his room clean and you often made jokes about it. With the shuffle of feet and a click sound sans locked the door, you were sitting on the bed smiling, this was going to be fun. He handed over the potion, this made you surprised however, you drank it and waited for the effect to work.  
While waiting you decided to stroke his spine and ribs, he made soft gasps and you began to trace his pelvis with your fingers. At this point the potion was starting to kick in and you realized that after not needing to catch your breath while he squeezed your breasts. You told him that it was working and he responded with his normal grin but with a devious glare in his eyes. He undressed you and laid you on the bed, then took off his own clothes and told you to close your eyes. You close your eyes and feel something at the tip of your lips, you open up and try to suck on it. Before you can suck it enters your throat, going deeper into you while he reaches over and grabs a few sex toys. You feel a cloth wrap around your eyes and a bonus finger at the edge of your vagina, slowly shoving in a vibrator. Then the fingers guide themselves into your ass, feeling about and then pulling out and replacing themselves with a but plug. Now, with all of your holes filled you can't help but wonder what will happen next. He forces more into your mouth and you realize, this isn't a penis, it's a tentacle. You think for a second about how he probably saw this in a hentai and get curious about what he's going to do. You realize that you wouldn't have been able to breathe with this much in you, glad for the potion. Your saliva doesn't seem like enough to cover the tentacle as he pushes it into you deeper, now feeling it in your chest. How deep was he going to go? He continues letting it guide it's self deeper into your body, you abdomen bulging slightly as it enters your stomach. You find it increasingly hard to focus on the tentacle as you become pleasured by the vibrator. The tentacle then fills your small intestine, making your belly very tight and bulging. Sans then removes the vibrator and sticks his fingers inside, you were surprised your wetness wasn't dripping down your vagina. You notice a sharp pain as the tentacle begins to fill your large intestine, having your stomach bulging outwards so far that you probably looked like a woman in their third trimester of pregnancy. Sans removes his fingers from your wet pussy and starts touching your breasts. Your body clenches harder on the but plug as you feel that you may explode from all of the pressure inside of you. Then after what feels like forever you feel the but plug forced out of your ass and a tentacle crawling out.  
Sans was no longer touching you, completely focused on his magic, which left you wondering what was going to happen next. You twitch at the feeling of the tentacle pressing gently against your tight wet entrance. Then without mercy the tentacle pounds into your pussy, going as deep as possible and faster than you could ever imagine. Part of the tentacle breaks off and begins playing with your clit while the other makes your walls whimper. The tentacle just seemed to be getting bigger and thicker the more it stretched your walls, as if it wants to make you its possession. Then the tip of the tentacle becomes super fine and slides its way into your cervix, into the uterus and without warning stretches immediately, making you cry and whimper loudly. The tip splits off again while the main part continues thrusting into your walls. The small tips then explore your ovaries and vibrate inside your tubes, giving the most pleasure you've ever had in your entire life. Sans then shoves his hand into your pussy, running his bony fingers against your walls to try to find your g spot. He quickly finds it and removes his hand but then re-inserts the vibrator to be pressed against it while the tentacles continue to pound into you without mercy. You feel yourself get tighter and tighter, right on the edge of an orgasm. Then the tentacles disappear and a thick magic penis replaces it and thrusts not into your walls but into the vibrator, putting extra pressure on your g spot and you cum. You faintly feel sans pounding into you and saying something but you're too full of pleasure. Then you notice your stomach start to bulge and feel the cock twitching inside your pussy, filling you with a hot thick liquid. Sans had just cum in you and it was so much and you had been craving it. Then he pulls out and unties the blindfold and you realize that you have to breathe.  
Sans laughs as you just lay on the bed staring at the ceiling. This was definitely something you could look forward to repeating. He helps you up and into the shower and you turn on the water as he leaves the room, finally able to see. You gently press on your stomach and have his cum leak down your leg, this was definitely worth trying again.


End file.
